Polycarbometallane

ABSTRACT

A polymer having a backbone repeat unit that includes at least two metal atoms bonded to each other and only one ethylenically unsaturated functional group wherein the backbone unit preferably has a structure of 
     
       
         —C(R 3 )═C(R 3 )—[C(R 3 )(R 4 )] n —[M(R 1 )(R 2 )] a —[C(R 3 )(R 4 )] p — 
       
     
     wherein n is 0 to 4; a is at least 2; p is 0 to 4; R 1  and R 2  are each independently selected from hydrogen, halogen, lower alkyl having 4 or fewer carbon atoms, alkenyl having 4 or fewer carbon atoms, or aromatic having one ring; R 3  and R 4  are each independently selected from hydrogen and lower alkyl having 1 to 4 carbon atoms; and M is a metal atom selected from at least one of Sn, Ge, Pb, Hg, Ni, Pd, Pt, Cr, Fe, Co, Cu and Zn. 
     The polymer has at least 20 weight percent metal, preferably at least 50 weight percent metal, based on the weight of the polymer.

This application claims benefit of U.S. Provisional Patent ApplicationNo. 60/082,963 filed Apr. 24, 1998.

BACKGROUND OF THE INVENTION

Acyclic diene metathesis (ADMET) polymerization is a steppolycondensation process that has been used to obtain macromolecules. InADMET polymerization, a diene is efficiently condensed to an unsaturatedpolymer by the removal of a small olefin (usually ethylene).

SUMMARY OF THE INVENTION

There is provided according to the present invention a polymer having anethylenically unsaturated backbone repeat unit that includes at leasttwo metal atoms bonded to each other wherein the backbone repeat unitincludes only one ethylenically unsaturated functional group or theethylenically unsaturation is separated by at least one saturated carbonatom from the metal-to-metal atoms. Preferably, the polymer includes abackbone repeat unit having the formula:

—C(R³)═C(R³)—[C(R³)(R⁴) ]_(n)—[M(R¹)(R²)]_(a)—[C(R³)(R⁴)]_(p)—

wherein n is 0 to 4 or 0 to 50, preferably 2 to 50; a is at least 2; pis 0 to 4 or 0 to 50, preferably 2 to 50; R¹ and R² are eachindependently selected from hydrogen, halogen, lower alkyl having 4 orfewer carbon atoms, alkenyl having 4 or fewer carbon atoms, or aromatichaving one ring; R³ and R⁴ are each independently selected from hydrogenand lower alkyl having 1 to 4 carbon atoms; and M is a metal atomselected from at least one of Sn, Ge, Pb, Hg, Ni, Pd, Pt, Cr, Fe, Co, Cuand Zn.

The present invention also provides a method for making an ethylenicallyunsaturated polymer that includes at least two metal atoms bonded toeach other comprising reacting a diene monomer that includes apolymetallane segment in the presence of an effective catalyst to obtainthe polymer.

In particular, the polymers of the invention (III) are synthesized viaacyclic diene metathesis (ADMET) polymerization of telechelicpolymetallane dienes (I) catalyzed by olefin metathesis catalysts basedon organometallic complexes of transition metals such as Mo, W, Ta, Ti,Ru (II), Re, Os or Nb.

There are numerous known metathesis catalysts that might be useful inthe invention. Transition metal carbene catalysts are well known.Illustrative metathesis catalyst systems include rhenium compounds (suchas Re₂O₇/Al₂O₃, ReCl₅/Al₂O₃, Re₂O₇/Sn(CH₃)₄, and CH₃ReO₃/Al₂O₃—SiO₂);ruthenium compounds (such as RuCl₃, RuCl₃(hydrate),K₂[RuCl₅—H₂O],[Ru(H₂O)₆](tos)₃(“tos” signifies tosylate),ruthenium/olefin systems (meaning a solution or dispersion of preformedcomplex between Ru and olefin (monomer) that also includes a β-oxygen inthe presence or absence of a soluble or dispersed polymer where thepolymer can be an oligomer or higher molecular weight polymer preparedby metathesis or other conventional polymerization synthesis), andruthenium carbene complexes as described in detail below); osmiumcompounds (such as OsCl₃, OsCl₃(hydrate) and osmium carbene complexes asdescribed in detail below); molybdenum compounds (such as molybdenumcarbene complexes (such as t-butoxy and hexafluoro-t-butoxy systems),molybdenum pentachloride, molybdenum oxytrichloride, tridodecylammoniummolybdate, methyltricaprylammonium molybdate, tri(tridecyl)ammoniummolybdate, and trioctylammonium molybdate); tungsten compounds (such astungsten carbene complexes (such as t-butoxy and hexafluoro-t-butoxysystems), WCl₆ (typically with a co-catalyst such as SnR₄ (R signifiesalkyl) or PbR₄), tungsten oxytetrachloride, tungsten oxidetridodecylammonium tungstate, methyltricaprylammonium tungstate,tri(tridecyl)ammonium tungstate, trioctylammonium tungstate,WCl₆/CH₃CH₂OH/CH₃CH₂AlCl₂, WO₃/SiO₂/Al₂O₃,WCl₆/2,6—C₆H₅—C₆H₅OH/SnR₄WCl₆/2,6-Br—C₆H₃OH/SnR₄,WOCl₄/2,6-C₆H₅—OH/SnR₄, WOCl₄/2,6-Br—C₆H₃OH/SnR₄); TiCl₄/aluminum alkyl;NbO_(x),/SiO₂/iso-butyl AlCl₂; and MgCl₂. As indicated above, some ofthese catalysts, particularly tungsten, require the presence ofadditional activator or initiator systems such as aluminum, zinc, leador tin alkyl. Preferred catalysts are ruthenium compounds, molybdenumcompounds and osmium compounds.

Telechelic polymetallane dienes (I) may be synthesized using any singleor a combination of the following procedures according to the invention:

1) The use of alkenyl metallanes (IV) as chain limiters in thedehydrogenation of metal dihydrides (V) catalyzed by organometalliccomplexes of transition metals such as Zr, Ti, Rh, Pt, Pd, Ni, V, Hf, Scor Ta (VI).

2) The use of alkenyl metal halides (VII) as chain limiters in theWurtz-type coupling of metal dihalides (VIII) in the presence of alkalimetals such as Li, Na, K, Rb or Cs (IX).

3) The sequential alkenylation of polymetallane dihalides (XI) byorganometallic reagents bearing the alkenyl moiety (X) (w and y areindependently any number between 2 and 50).

The coupling of alkenyl metallanes (IV) with metal diamides (XII).

 In all schemes:

M is a metal atom selected from at least one of Sn, Ge, Pb, Hg, Ni, Pd,Pt, Cr, Fe, Co, Cu and Zn;

R₁ and R₂ are independently hydrogen, alkyl or aryl groups containing 2to 50 carbons;

w and y are independently any number between 2 and 50;

x and n are independently any number larger than 1;

X is a halogen atom such as Cl, Br or I;

E is any electrophile consisting of or containing metals such as Li, Na,K, Cs, Mg, Zn, Cd or Hg.

In each of these schemes it is possible to use a mixture of reactantsthat could have different divalent radicals ( )_(w) and ( )_(y) whereinthe number of carbon atoms varies. In addition, R₁ and R₂ could bebonded to form a cyclic structure to the same metal atom or to adjacentmetal atoms.

Another possible synthetic route to suitable polymetallane monomers isto use cyclopolymetallane reactants and (1) subject them to UVradiation, (2) two step reaction with CH₂═CH(CH₂)_(n)E and thenCH₂═CH(CH₂)_(n)X (wherein n, E and X are the same as identified above),and (3) reacting with CH₂═CH(CH₂)_(n)M(X)₂(CH₂)_(n)CH═CH₂.

The polymer should have a high amount of metal, at least about 20 weight%, preferably at least about 50 weight %, based on the weight of thepolymer. Polymers with such a structure should have very advantageouselectrical and thermal conductivity properties and thus can be used inconductive films, fibers and solders and photoresists. In addition, theyshould be malleable and easy-to-process since they are very soluble inorganic solvents and should have good melt processing characteristics.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first step in our approach to ADMET polymers containingpolymetallane segments consists of the design and synthesis of suitablediene monomers containing at least one metal-metal σ bond. In order todetermine the compatibility between this functionality and themetathesis catalysts employed in the polymerization, we haveconcentrated our efforts on the preparation of di- and tristannanedienes. The alkenylation of a tri- or distannane dichloride appearedattractive to us since a variety of carbonated segments can beintroduced by the choice of the alkenylating group.

The synthesis of monomer of formula 2 as shown in Scheme 1 belowinvolves the in situ generation of Bu₂SnHCl, its dehydrogenativecoupling to the distannane dichloride, and the subsequent reaction ofthis dichloride with a nucleophilic alkenyl group, and we have attemptedto reduce this procedure to a one-pot synthesis scheme based on thedifficulties often associated with the purification of tin halides.

The room temperature disproportionation of equimolar amounts of Bu₂SnCl₂and Bu₂SnH₂ leading to Bu₂SnHCl has been previously reported in Newmann,W. P.; Pedain, J. Tetrahedron 1964, 36, 2461; (b) Kawakami, T.; Suimoto,T.; Shibata, I.; Baba, A.; Matsuda, H.; Sonoda, N. J. Org. Chem. 60,2677 (1995). The equilibrium concentrations are reached in ca. 10 min at25° C. Addition of a catalytic amount of dry pyridine or a Pd complex tothis mixture has also been reported in Newmann et al. to cause thequantitative decomposition of the Bu₂SnHCl to the distannane dichloride.The palladium catalyzed coupling appears to be the most efficient, andBu₄SN₂CL₂ solutions are obtained after—often vigorous—hydrogen evolutionfrom the precursor Bu₂SnHCl solutions. This disappearance of the signalcentered at 44.6 ppm and the simultaneous appearance of a new sharpsinglet at 109.0 ppm in the (proton decoupled) ¹¹⁹Sn-NMR(1J¹¹⁹Sn−¹¹⁹Sn=2420 Hz), have proven to be very useful in the monitoringof this reaction. We have also observed that this methodology can beextended to other polystannane dichlorides, which can be used asprecursors for diene monomers.

The alkenylation of the distannane dichloride is a facile reaction.Gentle reflux of the dichloride with the Grignard reagent generated from5-bromo-1-pentene affords after workup a mixture of the dienes offormulae 2,3, and 4 identified by their distinct resonances in the¹¹⁹Sn-NMR. However, we have been unable to produce 2 free of otherdienes, and attempts to separate these dienes have also provenunsuccessful. Bu₂SnCl₂ remaining from the incomplete disproportionationreaction accounts for the presence of formula 3, while the coupling ofremaining Bu₂SnH₂ with Bu₂SnHCl in the second step explains the presenceof diene of formula 4. To our surprise, these compounds are quite stablenot only to aqueous workup of the Grignard reaction, but also toadsorbents such as silica gel, which allows their isolation in adequatepurity for ADMET polymerization.

Upon exposure to the molybdenum catalyst 1, this purified diene mixtureproduced the ADMET terpolymer of formula 6 in almost quantitative yield.(see Scheme 2 below) Ethylene evolution is very vigorous during thefirst 4 h of the reaction, and the viscosity of the reaction mixtureincreases steadily suggesting polymerization. After this time, ethylenebubbling rate decreases, but continues throughout the reaction untilviscosity prevents magnetic stirring. Characterization of the crudepolymer sample reveals that polymerization has indeed taken place, alongwith the incorporation of the three stannadienes 2,3 and 4. Both ¹³C and¹H-NMR of the polymer show the conversion from terminal dienes tointernal olefins. New signals at 5.5-5.6 ppm (¹H), and at 131.2 and130.6 ppm (¹³C) account for the new olefin linkages, in both cis andtrans isomeric forms. Polymerization is also evident by the splitting ofthe ¹¹⁹Sn signals originally present in the monomer mixture, due to theslightly different magnetic environments caused by the olefin linkages.

Precipitation of the polymers from CDCl₃ or C₆D₆ solutions into methanolyields the polymers as viscous liquid samples. End group analysis basedon NMR Spectroscopy suggests an average degree of polymerization of 20.(Calculated Mn=11,000 g/mol).

EXAMPLE

Mo(CHCMe₂Ph)(N-2,6-C₆H₃—Pr₂)(Ocme(CF₃)₂)₂ (catalyst 1) anddi-n-butylstannane were synthesized according to, respectively, Schrock,R. R., Murdzek, J. R., Bazan, G. C., DiMare, M., O'Regan, M. J. Am.Chem. Soc., 112, 3875 (1990) and Imori, T., Lu, V., Cai, H., Tilley, T.D., J. Am. Chem. Soc., 117, 9931 (1995), both incorporated herein byreference. 5-Bromo-1-pentene was purchased from Aldrich Chemical Companyand distilled from CaH₂ immediately before use. Di-n-butyltin dichloridewas purchased from Acros Organics and used as received. Diethyl etherwas distilled from sodium benzophenone ketyl and stored over 4 Åmolecular sieves in an inert atmosphere of argon.

¹H (300 MHz), ¹³C(75 Mhz), and ¹¹⁹Sn (112 MHz) NMR was performed on avarian VXR-300 MHz superconducting spectrophotometric system usingdeuterobenzene (C₆D₆) as the solvent. ¹H and ¹³C NMR are referenced toan internal 0.05% w/w TMS standard while ¹¹⁹Sn NMR are referenced to aninternal 1% w/w tetramethyltin sample.

Synthesis of 6,6,7,7-tetrabutyl-6,7-distanna-1,11 -dodecadiene (formula2)

In a flame-dried schlenk tube, a solution of 1.24g (4.05 mmol) ofBu₂SnCl₂ in 6 mL of anhydrous diethyl ether was added via syringe toneat Bu₂,SnH₂, (1.01 g, 4.26 mmol), and this mixture was stirred underan argon atmosphere for 15 min. Dry pyridine (33 μL, 0.40 mmol) wasadded, and the mixture was stirred for an additional 4 h. The solventwas removed in vacuo and the colorless liquid obtained was weighed andredissolved in 5 mL of diethyl ether to make solution 1.

A suspension of powdered Mg (0.294 g, 12.11 mmol) in diethyl ether (6mL) was kept in a flame-dried three-neck round bottomed flask under anargon atmosphere. A solution of freshly distilled 5-bromo-1-pentene(1.67 g, 11.18 mmol) in diethyl ether (6 mL) was then slowly added andthis mixture was refluxed for 2 h, time after which Solution 1 wasslowly dropped using an addition funnel. The resulting mixture wasrefluxed for 20 h, cooled to room temperature and the supernatantsolution was cannula-filtered to a schlenk tube. Addition of pentane (15mL) and a second cannula filtration afforded a solution which was washedtwice with ice-cold 1 M NH₄CL (2×15 mL), dried over MgSO₄ and filteredthrough a pad of silica gel. The solvent was removed in vacuo and 1.44 g(64%) of a colorless viscous liquid were obtained. This product(material 5) is a mixture of the three tin containing dienes6,6-dibutyl-6-stanna-1, 10-undecadiene (material 3),6,6,7,7-tetrabutyl-6,7-distanna-1, 11-dodecadiene (material 2), and6,6,7,7,8,8-hexabutyl-6,7,8-tristanna-1,12-tridecadiene (material 4) inan undetermined ratio. ¹H NMR: d(ppm)=5.7-5.9 (m, 2 H); 5.0-5.2 (m, 4H); 2.0-2.2 (m, 4 H); 1.6-1.9 (m); 1.3-1.6 (m); 1.3-1.1 (m); 0.8-1.1(m). ¹³C NMR: d(ppm)=139.2, 115.5, 39.5, 33.9, 31.7, 30.2, 28.9, 28.5,27.5, 14.5, 11.6-11.3, 10.9-10.6, 9.6-9.3. ¹¹⁹Sn NMR; d(ppm)=−12.4 (3,C—Sn—C), −76.4 (4, C—Sn—Sn—Sn—C), −83.5 (2, C—Sn—Sn—C), −227.3 (4,C—Sn—Sn—Sn—C). Elemental anal. for C₂₆H₅₄ Sn ₂ (2). Calcd: C(51.70%),H(9.01%). Found: C(51.67%), H(8.76%). HR-MS for C₂₂H₄₅ Sn ₂ (2)-C₄H₉.Calcd: 547.1579 m/z (Average of two analysis).

ADMET Polymerization of mixture of formula 5.

In an argon purged dry box, catalyst 1 (5 mg) was weighed and placed ina 50 mL round bottomed flask adapted with a Rotoflow valve. The monomermixture (in other words, formula 5) (400 mg) was then added to the flaskwhich was in turn sealed and taken to a high vacuum schlenk line.Ethylene evolution could be evidenced at room temperature during thefirst 12 h of reaction. After this time, the system was heated to 60° C.and the reaction was continued for 24 h. The reaction was stopped byremoval of the heat when magnetic aggitation became impossible or whenno further bubbling could be evidenced, and the crude viscous polymericproduct of formula 6 was dissolved in C₆D₆ ¹H NMR: d(ppm)=5.5-5.6 (b);2.0-2.4 (b); 1.6-1.9 (m); 1.3-1.6 (m); 1.3-1.1(m); 0.8-1.1 (m). ¹³C NMR:d(ppm)=131.2, 130.6, 38.7, 38.5, 33.9, 31.7, 30.3, 28.9, 28.5, 14.5,11.6, 112.0, 9.6. ¹¹⁹Sn NMR: d(ppm)=−11.5, −11.6, −11.8, −75.4, −75.5;−82.6, −82.8, −82.9, −83.0; −226.3, −226.4. Elemental anal. for(C₆H₅₀Sn₂)_(n). Calcd: C(50.04%), H(8.75%). Found: C(%), H(%).

It should be recognized that the polymeric product of formula 6 is adistribution of polymer chains wherein a portion of the chains will alsoinclude a backbone unit that has only one metal atom. However, suchpolymer chains also will include backbone units with at least two metalatoms as per the invention.

Scheme 1. Synthesis of monomer 2. Alkylation of residual Bu₂SnCl₂accounts for the formation of material 3 (m=2 in formula 5 below). Thepyridine-catalyzed coupling of Bu₂SnH, with Bu₂SnHCl in step 3 wouldyield a tristannane dichloride, a precursor to material 4(m=3 in formula5 below).

Scheme 2. ADMET polymerization of the monomer mixture 5 to theterpolymer 6.

What is claimed is:
 1. A polymer having a backbone repeat unit thatcomprises at least two metal atoms bonded to each other and only oneethylenically unsaturated functional group produced by a cyclic dienemetathesis polymerization.
 2. A polymer according to claim 1 wherein themetal atoms are selected from a group consisting of Sn, Ge, Pb, Hg, Ni,Pd, Pt, Cr, Fe, Co, Cu and Zn.
 3. A polymer according to claim 1 whereinthe polymer comprises at least about 20 weight percent metal, based onthe weight of the polymer.
 4. A polymer according to claim 3 wherein thepolymer comprises at least about 50 weight percent metal, based on theweight of the polymer.
 5. A polymer according to claim 1 wherein thebackbone repeat unit has a structure represented by:—C(R³)═C(R³)—[C(R³)(R⁴)]_(n)—[M(R¹)(R²)]_(a)—[C(R³)(R⁴)]_(p)— wherein nis 0 to 50; a is at least 2; p is 0 to 50; R¹ and R² are eachindependently selected from hydrogen, halogen, lower alkyl having 4 orfewer carbon atoms, alkenyl having 4 or fewer carbon atoms, or aromatichaving one ring; R³ and R⁴ are each independently selected from hydrogenand lower alkyl having 1 to 4 carbon atoms; and M is a metal atomselected from a group consisting of Sn, Ge, Pb, Hg, Ni, Pd, Pt, Cr, Fe,Co, Cu and Zn.
 6. A polymer according to claim 2 wherein the metal atomsare Sn.
 7. A polymer according to claim 5 wherein the metal atoms areSn.
 8. A polymer having a backbone repeat unit that comprises at leasttwo metal atoms bonded to each other and an ethylenically unsaturatedfunctional group separated by at least one saturated carbon atom fromthe metal-to-metal atoms.
 9. A polymer according to claim 5 wherein nand p are each independently 0 to
 50. 10. A polymer according to claim 5wherein n and p are each independently 0 to 4.